Hydraulic press with high and low capacity reciprocating fluid motors in tandem

ABSTRACT

A hydraulic press comprising high and low capacity reciprocating motors structurally connected in tandem and independently controlled. With this construction, the high capacity motor provides high-tonnage forming forces, while the low capacity motor provides more accurate forming forces at low tonnages.

United States Patent [72] Inventor Jerome E. Balkee Fountain Valley, Calif.

211 App]. No. 844,287

[22 Filed July 24. 1969 [45] Patented Aug. 31, I971 [73] Assignee Murdock, Inc.

Compton, Calif.

[54] HYDRAULIC PRESS WITH HIGH AND LOW CAPACITY RECIPROCATING FLUID MOTORS IN TANDEM 3 Claims, 2 Drawing Figs. [52] 11.5. CI 91/411A, 92/152. 60/52 HF. 60/97 H [51] 1nt.C| v. lF15b11/l6 [50] Field of Search 81/411 A,

41 1; 92/152; 60/97 H 52 HF [56] References Cited UNITED STATES PATENTS 1,430,359 9/1922 Canion 60/97 H UX 2,453.785 11/1948 Cousino 91/411 X 2,484,879 10/1949 Ernst et a1 91/411 A X 2,934,380 4/1960 Julieretal 60/97 H UX Primary Examiner Edgar W. Geoghegan Attorney-Harris. Kiech Russell & Kern ABSTRACT: A hydraulic press comprising high and low capacity reciprocating motors structurally connected in tandem and independently controlled. With this construction, the high capacity motor provides hightonnage forming forces. while the low capacity motor provides more accurate forming forces at low tonnages.

PATENTEU AUG31 :97:

lNl/ENTOR. JEROME E. BHLKEE BY H13 HTTQRNAEKS. HARP/S, /f/CH, RUSSELL 8: KER/v HYDRAULIC PRESS WITH HIGH AND LOW CAPACITY RECIPROCATING FLUID MOTORS IN TANDEM SUMMARY AND OBJECTS OF INVENTION The present invention relates in general to a fluid operated actuator, particularly for a hydraulic press, and the primary object of the invention is to provide large main and small auxiliary fluid operated motors of the reciprocating type structurally connected in tandem and operable independently of each other. With this construction, the main motor can be used to develop large forces, and the auxiliary motor can be used when accurate small forces are desired, which is an im portant feature of the invention.

More particularly, an important object of the invention is to provide a tandem hydraulic press comprising a stationary main cylinder containing a large main piston and comprising an auxiliary cylinder axially aligned with and movable axially of the main cylinder and containing a small auxiliary piston connected to the main piston. Means are provided for applying hydraulicpressures to the main and auxiliary pistons inde- ,pendently of each other. Pressure can be applied to the large piston to produce large tonnages. Should small tonnages slightly larger than the weight of the upper bolster and platen assembly of the press be desired, pressure can be introduced to the lower port of the auxiliary cylinder to produce a more accurate small tonnage of this magnitude. Should small tonnages be required which are less than the weight of the upper bolster and platen assembly, the pressure may be introduced I DESCRIPTION OF DRAWING In. the drawing:

FIG. 1 is an elevational view on a reduced scale showing a tandem fluid operated actuator of the invention incorporated in a conventional hydraulic press; and

FIG. 2 is an enlarged, vertical sectional view showing the tandem fluid-operated actuator of the invention in more detail.

DESCRIPTION OF EXEMPLARY EMBODIMENT OF INVENTION In the drawing, the numeral designates generally a hydraulic press incorporating a C-shaped supporting structure 12 provided with upper and lower arms 14 and 16 respectively carrying an upper bolster and platen assembly 18 and a lower platen assembly 20. More particularly, the upper assembly 18 is carried by andis movable toward and away from the lower assembly 20 by a tandem fluid-operated, preferably hydraulic, actuator 22 of the invention mounted on the upper arm 14 of the supporting structure 12.

The tandem actuator 22 includes a high capacity, or high tonnage," main hydraulic. motor 24 of the reciprocating type, and a low capacity, or low tonnage," auxiliary hydraulic .motor 26 of the reciprocating type, the two motors being structurally connected in tandem and independently operated.

More particularly, the main motor 24 comprises a vertical, stationary, main cylinder 28 carried by the supporting structure arm 14. Reciprocable in the main cylinder 28 is a main piston or ram 30. Upper and lower hydraulic lines 32 and 34 are connected to the upper and lower ends of the main cylinder28 and are controlled by a suitable control means 36, exemplifiedas a fourway selector valve.

A piston rod means 40, shown as comprising interconnected upper and lower piston rods 42 and 44, connects an auxiliary piston 46 to the main piston 30, the auxiliary piston being considerably smaller than and axially aligned with' the main piston. The auxiliary piston 46 isreciprocable in an auxiliary cylinder 48 which is axially aligned with and movable axially relative to the stationary main cylinder 28. Upper and lower hydraulic lines 50 and 52 are connected to the upper and lower ends of the auxiliary cylinder 48 and are controlled by a suitable control means 54 similar to the control means 36.

The auxiliary cylinder 48 is mounted in a tubular carriage means 56 which is connected at its lower end to the upper bolster and platen assembly 18, and which is mounted on the supporting structure arm 14 for vertical sliding movement, axially of the main cylinder 28, by suitable bearing means 58. The rod means 40 carries, at the junction of the upper and lower piston rods 42 and 44, a guide means 60 which is axially reciprocable in the upper end of the tubular carriage means 5 6, between annular stops 62 and 64.

EXPLANATION or OPERATION Method 1 The control means 36 is operated to produce an adjustable high downward force in the rod 42. This high force, which is generated due ta pressure exerted on piston 30 is transmitted, through the guide means 60 and the annular stop 62, to the carriage 56. The carriage further transmits this high force to the upper assembly 18 and ultimately to the workpiece between the upper and lower assemblies 118 and 20.

The forming force generated by the above method of operation is the product of the hydraulic pressure in the cylinder 28 and the area of the piston 30, plus the weight of the piston 30, the piston rod 42, and all of the weight suspended from the piston rod 42. The formula for this force is F=( P A +W, where F=Force applied to the workpiece,

P=Pressure cylinder 28,

A=Area of piston 30, and

W=Weight of piston 30, piston rod 42 and all weight suspended from piston rod 42. F may, for example, range from 20 tons to as high as tons, or more, it being understood that these values are illustrative only. Method 2 For generating smaller, more accurate tonnages which are additive to the suspended weight, the main hydraulic motor 24 is hydraulically locked, and an adjustable pressure is then introduced in the hydraulic line 52. This applies a downward force to the carriage 56, which in turn transmits the force to the upper bolster and platen assembly 18.

The force generated by this method of operation is the product of the hydraulic pressure in the line 52 and the area of the piston 46, plus the weight of the cylinder 48 and all items suspended therefrom. The formula for this force is F=(P XA) +W, where F=Force applied to the workpiece,

=Area of piston 46, P==Pressure in line 52, and W=Weight ofcylinder barrel 48, carriage 56, and upper bolster and platen assembly 18, i.e., any items suspended from cylinder 48. Merely to illustrate, if W is of the order of 10 tons, F may range from 10 to 20 tons. Method 3 For generating forces which require a tonnage less than the suspended weight, the main hydraulic motor 24 is again locked and an adjustable pressure is then introduced in the hydraulic line 50. This creates an upward force equal to the product of the pressure and the net area of piston 46. The downward force consists of the weight of the cylinder 48 and all items suspended therefrom.

The resultant of these two forces is transmitted to the workpiece through the upper bolster and platen assembly 18. The formula for this resultant force is F=W[PX(AA' )1,

where F=Force applied the workpiece,

=Area of piston 46,

A'= Area ofpiston rod 44,

#Pressure in-line 50, and

W=Weight of cylinder 48, carriage 56, upper bolster and platen assembly 18 and any other weight suspended from cylinder 48. F in this case may range from virtually zero to, for example,

tons.

SUMMARY As seen from the formulas given in the three methods of operation, three different piston areas are available for use in pressing operations.

Since the force is the product of the pressure and the area, it is obvious that any variation in the pressure will result in a large variation in the force if used with a large area (Method 1 )4 By decreasing the area by using Methods 2 and 3, the total error in force will be less assuming that the pressure tolerance remains constant in all three methods.

What is claimed is:

1. A tandem hydraulic press comprising a stationary main cylinder containing a main piston and an auxiliary cylinder ax ially aligned with and movable axially of said main cylinder and containing an auxiliary piston, rod means fixedly connecting said auxiliary piston to said main piston and maintaining a fixed positional relation therebetween, and means for applying hydraulic pressures to said pistons independently of each other 2. In a tandem hydraulic press, the combination of:

a. a supporting structure;

b. a stationary main cylinder carried by said supporting structure;

c. a main piston reciprocable in said main cylinder;

d. an auxiliary piston axially aligned with said main piston;

6. rod means fixedly connecting said auxiliary piston to said main piston and maintaining a fixed positional relation therebetween;

f. an auxiliary cylinder axially aligned with said main cylinder and containing said auxiliary piston;

g. means mounting said auxiliary cylinder for axial movement relative to said main cylinder and said auxiliary piston; and

h. means for applying hydraulic prcssureto said pistons independently of each other.

3. A tandem hydraulic press as set forth in claim 2 wherein said mounting means includes:

a. tubular carriage means for said auxiliary cylinder;

b. bearing means slidably mounting said tubular carriage means on said supporting structure for movement axially of said main cylinder 0. guide means carried by said rod means within and slidable axially relative to said tubular carriage means; and

d. stop means on said tubular carriage means and engageable by said guide means. 

1. A tandem hydraulic press comprising a stationary main cylinder containing a main piston and an auxiliary cylinder axially aligned with and movable axially of said main cylinder and containing an auxiliary piston, rod means fixedly connecting said auxiliary piston to said main piston and maintaining a fixed positional relation therebetween, and means for applying hydraulic pressures to said pistons independently of each other
 2. In a tandem hydraulic press, the combination of: a. a supporting structure; b. a stationary main cylinder carried by said supporting structure; c. a main piston reciprocable in said main cylinder; d. an auxiliary piston axially aligned with said main piston; e. rod means fixedly connecting said auxiliary piston to said main piston and maintaining a fixed positional relation therebetween; f. an auxiliary cylinder axially aligned with said main cylinder and containing said auxiliary piston; g. means mounting said auxiliary cylinder for axial movement relative to said main cylinder and said auxiliary piston; and h. means for applying hydraulic pressure to said pistons independently of each other.
 3. A tandem hydraulic press as set forth in claim 2 wherein said mounting means includes: a. tubular carriage means for said auxiliary cylinder; b. bearing means slidably mounting said tubular carriage means on said supporting structure for movement axially of said main cylinder c. guide means carried by said rod means within and slidable axially relative to said tubular carriage means; and d. stop means on said tubular carriage means and engageable by said guide means. 